1. Technical Field
The present disclosure relates to a proton conductor.
2. Description of the Related Art
Among proton conducting solid electrolytes, many perovskite-type proton conducting oxides have been reported which are expressed by the compositional formula AB1-xB′xO3-δ. Herein, A is an alkaline-earth metal; B is a tetravalent group 4 transition metal element, or Ce, which is a tetravalent lanthanoid element; B′ is a trivalent group 3 or group 13 element; and O is oxygen. x is a mole fraction of the B′ element with which the B element is substituted, satisfying 0<x<1.0. δ is a value representing oxygen deficiencies or oxygen excesses. The fundamental construction of a perovskite structure will later be briefly described with reference to the drawings.
Nature materials Vol 9 (October 2010) 846-852 discloses oxides of a perovskite structure. The oxides described in Nature materials Vol 9 (October 2010) 846-852 have the compositional formula BaZr1-xYxO3-δ or the compositional formula BaCe1-xYxO3-δ. In these oxides, A is barium (Ba); B is Zr or Ce; and B′ is Y.
Japanese Laid-Open Patent Publication No. 2008-23404 discloses a proton conducting film of a perovskite structure. The proton conducting film described in Japanese Laid-Open Patent Publication No. 2008-23404 has the chemical formula AL1-XMXO3-α. A is an alkaline-earth metal. L is one or more kinds of elements selected from cerium, titanium, zirconium, and hafnium. M is one or more kinds of elements selected from neodymium, gallium, aluminum, yttrium, indium, ytterbium, scandium, gadolinium, samarium, and praseodymium. Herein, X is the mole fraction of an M element with which the L element is substituted, where α is an atomic ratio of oxygen deficiencies. In the proton conducting film described in Japanese Laid-Open Patent Publication No. 2008-23404, 0.05<X<0.35, and 0.15<α<1.00.